Fluid hydroforming



Jan. 25, 1955 J. wElKART 2,700,639

FLUIDj-IYDROFORMING Filed Dec. 26, 1951 2 Shee'tS-Sheet l @n C'Ltt'ofrlzJan. 25, 1955 J. wr-:IKART FLUID HYDROFORMING 2 Sheets-Sheet 2 FiledDec. 26, 1951 PRODUCT /REACTOR FEED ' RECYCLE GAS @f REGENERATION JohnWeikarf United IStates, Patent() 2,700,639 FLUID HYDRoFoRMlNG JohnWeikart, Westfield, N. J., assignor to Standard Oil Development Company,a corporation of Delaware Application December 26, 1951, Serial No.263,360 Claims. (Cl. 196-50) ess for treating hydrocarbon Byhydroforming is ordinarily meant an operation conducted at elevatedtemperatures and pressures in the presence of solid catalyst particlesand hydrogen whereby the hydrocarbon fraction is increased inaromaticity and in which operation there is no net consumption ofhydrogen. Hydroforming operations are ordinarilycarried out in thepresence of hydrogen or hydrogen-rich recycle gas at temperatures of750-l150 F. in the pressure range of about 50-1000 lbs. per sq. inch,and in contact with such catalysts as molybdenum oxide, chromium oxide,or, in general, oxides or sulfides of metals of groups IV, V, VI, VIIand VIII of the periodic system of elements alone, or generallysupported on a base or spacing agent such as alumina gel, precipitatedalumina or zinc aluminate spinel. A good hydroforming catalyst is onecontaining about l0 weight per cent molybdenum oxide upon an aluminumoxide base prepared by heat treating a hydrated aluminum oxide or upon azinc aluminate spinel.

It has been proposed in application Serial No. 188,236, led October 3,1950, to effect the hydroforming of naphtha fractions in a uidizedsolids reactor system in which naphtha vapors are passed continuouslythrough a dense, fluidized bed of hydroforming catalyst particles in areaction zone, spent catalyst particles being withdrawn from the densebed in the reaction zone and passed to a separate regeneration zonewhere inactivating carbonaceous deposits are removed by combustionwhereupon the regenerated catalyst particles are returned to the mainreactor vessel. Fluid hydroforming as thus conducted has severalfundamental advantages over fixed bed hydroforming such` as 1) theoperations are continuous, (2) the vessels and equipment can be designedfor single rather than dual functions, (3) the reactor temperature issubstantially constant throughout the bed and (4) the regeneration orreconditioning of the catalyst may be readily controlled.

. A particular advantage of the foregoing fluid solids fact that thefreshly regenerated to carry part of the necessary heat requirements forthe hydroforming reaction from the regeneration zone into the reactionzone. It has been proposed in this connection to discharge hot,regenerated catalyst particles from the regenerator standpipe into astream of hot, hydrogen-rich recycle gas in va transfer line whereby thecatalyst particles are subjected to a reconditioning treatment involvingat least a partial reduction of a higher oxide of the catalytic metalformed during regeneration to a form of lower oxide of the catalyticmetal which is more catalytically active during its passage through thetransfer line into the reaction zone. In view of the -high temperatureof the regenerated catalyst (1050-l200 F.) and the exothermic characterof the reaction between the hot, freshly regenerated catalyst and thelhydrogen-rich gas, it is necessary to make the transfer line of smalldiameter 2,700,639 Patented Jan." 25, 1955 and as short as possible inorder to keep the time of contact of the regenerated catalyst andhydrogen-containing gas sulciently short to avoid overtreatment and/orthermal degradation of the catalyst.

It is the object of this invention to provide a novel method fortreating freshly regenerated hydroforming catalyst preparatory torecycling the same to a uidized solids hydroforming reactor.

It is also the object of this invention to provide a method andapparatus whereby freshly regenerated hydroforming catalyst may betreated at relatively low temperatures while effectively utilizing thehot regenf erated catalyst for supplying at least about twenty-live percent of the heat required for the hydroforming reaction.

It is a further object of this invention to provide a simple method andapparatus whereby hot, freshly regenerated hydroformlng catalyst may beeffectively cooled prior to contact with hydrogen-containing gas andstill supply a substantial amount of the heat required for thehydroforming operation.

These and other objects will appear more clearly from the detailedspecication and claims which follow.

It has now been found that freshly regenerated hydroforming catalyst canbe pretreated with a hydrogen-containing gas at relatively lowtemperatures for any desired period while still effectively supplying apart of the heat required for the hydroforming reaction by irltermixingthe hot regenerated catalyst, preferably after stripping the same Ireeof combustion gases, with a stream of catalyst withdrawn from thereactor in suffcient amount to reduce the temperature of the regeneratedcatalyst to the level desired for the pretreatment and then contactingthe resultant catalyst mixture with a hydrogen-containing gas for asufficient period to partially reduce the catalytic metal oxide andconvert the same to its most catalytically active form whereupon thetreated mixture is discharged into the main reaction zone. ln this way,the freshly regenerated catalyst is readily brought to the temperaturemost suitable for the hydrogen pretreatment before contact withhydrogencontaining gas while at the same time the sensible heatcontained in the freshly regenerated catalystV is transferred to thereactor catalyst and conveyed thereby into the reaction zone therebyreducing the amount of heat that must be supplied to the reaction zoneby circulation of preheated or superheated recycle gas and/or bypreheating of the naphtha feed. The' reactor catalyst mixed with thefreshly regenerated catalyst also serves to absorb some of the heatgenerated by the action of the hydrogen upon the regenerated catalyst.

Reference is made to the accompanying drawings in which Fig. 1 is adiagrammatic illustration of one embodiment of this invention and Fig. 2is a diagrammatic illustration of a system in which the regeneratedcatalyst is recycled to the upper part ofthe dense luidized catalyst bedin the reactionzone.

In Fig. 1 of the drawing, 10 is a reactor vessel which may desirably bea vertical cylindrical vessel of considerable length and which ischarged with a hydroforming catalyst such as molybdenum oxide upon analumina support which is in a nely divided form and maintained as adense iiuidized turbulent bed 11 by the passage therethrough ofhydrogen-rich gas introduced through inlet line 12 and vaporizedhydrocarbons introduced through inlet line 13. A perforated plate orgrid 14 is preferably provided near the bottomv of the reactor vessel inorder to insure uniform distribution of the incoming constitutents overthe entire cross-section of the vessel. The bed 11 has a definite levelL and is superposed by a dilute or disperse phase 15 comprising gaseousor vaporous reaction products containing a small amount of catalystentrained therein. The reaction products are taken overhead from reactorvessel 10, preferably after passage through a cyclone separator 16 whichserves to knock out entrained catalyst which is then returned to thedensebed 11 via the dip pipe provided at the bottom of separator 16. Thereaction products pass overhead through line 17 to suitablefractionating, stabilizing and/or storage equipment.

Means are -provided for the withdrawal of a' stream of catalyst directlyfrom xthe .dense bed 11. This may be in the form of a cell or conduit 18arranged entirely within the reactor below the level .L of the dense bedas shown or it may extend above dense bed level L and be provided withone or more ports -or restricted passageways below level L for thedischarge of catalyst into said conduit. It .may alternatively comprisea conduit arranged externally of the reactor .and connected to the-reactor by means of a suitable connector conduit. A gas such as steam,nitrogen or the like is .supplied to conduit 1.8 at one or more pointssuch as 19 in order to strip out entrained reaction products orvaporizable materials from the spent catalyst particles and therebyminimize the amount of combustible material carried by the spentcatalyst to the regenerator.

The conduit 18 serves also as a standpipe .for developing the uistaticIpressure necessary to overcome the .pres sure ldrop through theregeneration system. Although the catalyst owing in the conduit orstandpipe 18 will ordinarily .carry entrained or trapped gas with it inan amount sucient Ito maintain it in freely flowing fluid condition oneor .more taps may be 4provided along the lower por'- tion thereof tofacilitate start-up of the equipment or to take care of emergencies thatmight arise. The .stripped spent catalyst is discharged from conduit 18throughslide valve 20 into spent catalyst riser 21 where it is picked upby astream of air or regeneration gas .supplied through inlet line 22and is conveyed into regenerator vessel 23. In -order to preventoverheating of the catalyst upon .contact with the .regeneration air,.generally not more than .about 15% to 40% of the total air required forregeneration .is supplied .through inlet line 22 to convey the spentcatalyst through riser 21 linto regenerator 23. The remainder of the airnecessary for regeneration is supplied lto regenerator 23 .through Linlet line 24. In order to insure uniform distribution of the .incomingairand catalyst over the entire cross-section of the regeneration vesselit may be desirable to provide aiperforated plate or-distribution gridY25 .at `the lower `end of :the regenerator vessel. The velocity tof theregeneration gases `through vessel 23 is so controlled .as to form adense, .fluidized, liquid simulating .bed A26 of .catalyst particlesland ,gas .having a definite level L' superposed b ya dlutewor-dispersephase 27. Regeneration gases are taken loverhead Ifrom .regenerator 23Ythrough `a Ycyclone separator 28 or the like which-removes entraned`catalyst and returns the .separated catalyst to the dense bed 26 viathe dip leg .attached to .the bottom 4of .the cyclone. 'Ihe regenerationvgases vare then lpassed via .outlet line 29 through apressure reducingor -release`valve30 and thence "i to i'a waste gas 'stack or to suitable.scrubbing land storage means if itis desired to utilize y.this gas `for.stripping in the system.

1n view of Athe .fact that .the .oxidative :reactions that occur in theregenerator generate more heat than -can normally .be transferred .tothe reactor yby the circulating catalyst :at ,low catalyst to .oilratios, without .exceeding safe .temperature limits, it -is generallyvadvisable to provide :cooling coils in Lthe'regeneratorvto control thetemperature therein. A very desirable arrangement `is fto provide aprimary cooling coil entirely `below fthe dense bedll'evel L and .asecondary cooling ucoil partly below and ipartly `above :the :dense bedllevel 1L' to permit adjustment 'of vthe heat Vexchange .capacity bysimply 'vary-ing the dense bed .level L .in the regenerator.

Regenerated catalyst `is `.withdrawn 'from dense bed 26 through conduitA31 which extends downwardly through the :dense bed `26, the grid member25 and the bottom of the regenerator vessel. Stripping gas is introducedinto conduit 31 .at .32 and. if desired. at further points along thetransfer .line 33. Stripping of the regenerated catalyst may the eiectedwith sair, .nitrogen or liuc gas or mixtures of these. It is :preferred.to introduce air at 32 lto strip and/.or .effect a .final .clean up ofthe regenerated rcatalyst and thenito .purge the stream of regeneratedcatalyst Eby introducing a :small -amount of nitrogen in the transferline .-33. Ifiue gas is used for stripping the regenerated catalyst. .itis ,preferred to wash'it free Akof carbon ydioxide andtcarbonzmonoxidesince :it Iisladvisable vto exclude these gases :from .the.reaction'zone 'The'flow of stripped regenerated catalyst 'throughstandpipe -or transfer line 33 Ais controlled by a slidevalve 34 or 'thelike.

A conduit 35 is arranged in the .upper l'part .oflreactor vessel 10 `for1thewithdrawal-of a second Istream .of reactor catalyst :particles:directly'from vthe :dense bed The gas or air only a part .of theparticular form of this withdrawal conduit is immaterial. The stream ofcatalyst particles withdrawn through .conduit 35 is passed downwardlythrough conduit 36. Stripping gas such as recycle gas, methane, or thelike is introduced at one or more points 37 in order to strip off orreduce the amount of hydrocarbon reactants entrained in this stream ofreactor catalyst.

The regenerated catalyst transfer line and standpipe 33 are connected toreactor catalyst circulation conduit or standpipe 36 at 38. In this waythe stream of stripped regenerated catalyst is mixed with the stream ofreactor catalyst in suicient amount to give a mixture of catalystparticles having a temperature below about 1050 F. and preferably aboutl000 F. The mixture of regenerated catalyst and reactor catalyst passesdownwardly through standpipe 39 and is discharged through control orslide valve 40 into inlet line 12 where the catalyst particles arepicked up by a stream of hydrogen-rich recycle gas and conveyed therebykthrough transfer line 12 into the reactor. In view of the loweredtemperature of the regenerated catalyst and the presence of about anequalamount or .more of recycle .reactor catalyst, theexothermicreaction between the lregenerated catalyst and hydrogen isreadily controlled and contact of the hydrogen-containing gas and therecycle or hydrogen-.containing gas may be continued for as long as l5minutes or more without adversely affecting the catalyst. Ordinarilycontact of the regenerated catalyst with hydrogen-containing gas .forfrom a few seconds to a minute or so will suice to effect thepretreatment or conversion of the regenerated catalyst to its .mostactive form.

It is not intended that shown in the schematic the invention be limited`to `that diagram of Fig. 2. For example, reactor solids are shown tocirculate externally from top to bottom of the dense bed, but smallchanges as illustrated in Fig. 2 would permit ilow from bottom to Atopto provide an inverse temperature gradient across the reactor bed.Furthermore, the cyclone .separator dip legs might provide all or aportion of the circulating solid stream.

Referring lto Fig. 2, the same basic two-vessel system is .illustratedand the corresponding parts bear the .same reference numerals as in Fig.Ll. In the .embodiment shown in Fig. 2 a catalyst withdrawal line 18 vis,arranged in the reactor, and this is provided with an inlet line 19 forthe introduction of stripping gas the same as in Fig. 1. However,instead of providing a separate .catalyst withdrawal well for supplyingreactor catalyst for lintermixture with the freshly regeneratedcatalyst, `reactor catalyst withdrawal line 41 is connected to thecatalyst withdrawal line ,18. This withdrawal line 41 may beprovidedwith a valve 42 for the control of the supplyof reactor vcatalyst tostandpipe 39 and for intermixture with freshly regenerated catalyst. Inthis 4embodiment the mixture of reactor catalyst and freshly regeneratedcatalyst '-is not-discharged from standpipe 39 into the main stream ofrecycle gas ,forrecycling to the .bottom of the reactor vessel, but -istransferred'through a U-bend 43 or the like and riser line44 to theupper part of reactor dense bed y11. `Re cycle gas, asmall part of the.total recycle gas supplied to the reaction zone, .can be introduced.through line `45 to assist inconveyingthe mixture ofregenerated 'andreactor catalyst through the riser line 44 to the upper ypart of the.main reactor ldense bed. The major portion `of the .recycle gas vissupplied to the reactor through inlet line 46, while the preheated.naphtha vapor feed iis supplied through inlet line 47 toa distributorring or theflike for insuring uniform distribution of naphtha over `theentire cross section of the reactor vessel 10.

Fllie .feed .or charging stock to .the hydroforming reactor may be avirgin naphtha, a cracked naphtha, a FischerlTropsch naphtha `or thelike. The -feed stock is preheated .alone or in 'admixture with recyclegas to reaction temperature or to the maximum'temperature possible whileavoiding thermal degradation ofthe feed stock. Ordinarily preheating 'ofthe feed Lstock is -carried lout to temperatures yof Vabout 8009-1050F., vpreferably about Vl000 F. The naphtha preheat -should '-be as .high:as lpossible while vavoiding lthermal degradation thereof as .bylimiting :the time of residence in lthe furnace :and vtransfer for feedinlet lines. The preheated feed 'stock may be supplied to the reactionvessel for admixture with vhydrogen-rich recycle #gas below the gridmember "1.4 or it may be introduced through a distributor v ring,:ordre-like, arranged above the grid. The lrecycle i reactor should beabout 0.5 to

. 5 gas, which contains from about 50 to 80 vol. per cent hydrogen ispreheated to temperatures of about 11.50- 1300 F., preferably about 1200F., prior to the introduction thereof into inlet line 12. The recyclegas should be circulated through the reactor at a rate of from about1000 to 8000 cu. ft. per barrel of feed. The amount of recycle gas usedis preferably the `minimum amount that will suice to introduce thenecessary heat of reaction and keep carbon formation at a low level.

The reactor system is charged with a mass of finely divided hydroformingcatalyst particles. Suitable catalysts include group VI metal oxides,such as molybdenum oxide, chromium oxide or tungsten oxide or mixturesthereof upon a carrier such as activated alumina, zinc aluminate spinelor the like. Preferred catalysts contain about 5 to 15 weight per centmolybdenum oxide or from about 10 to 40 weight per cent chromium oxideupon a suitable carrier. If desired minor amounts of stabilizers andpromoters such as silica, calcium oxide, ceria or potassia can beincluded in the catalyst. The catalyst particles are, for the most part,between 200 and 400 mesh in size or about -200 microns in diameter witha major proportion between 20 and 80 microns.

The hydroforming reactor vessel should be operated at temperaturesbetween about 850 and 925 F., preferably about 900 F. and at pressuresbetween 50 and 500 lbs. per sq. inch, preferably about 200 lbs. per sq.inch. Temperatures above 900 F. result in increased carbon formation andlower selectivity to gasoline fractions while at temperatures belowabout 900 F. operating severity is low and would therefore require anexcessively large reaction vessel. Lowering reactor pressure below 200lbs. per sq. inch ordinarily results in increased carbon formation whichbecomes excessive in most cases at pressures below about 75 lbs. per sq.inch. Above 200 lbs., however, catalyst selectivity to light products(Cis and lighter) increases rapidly. The regenerator vessel is normallyoperated at essentially the same pressure as the reactor vessel and attemperatures of about 10501200 F The residence time of the catalyst inthe reactor is of the order of from 2 to 4 hours and in the regeneratorof from about 3 to 15 minutes.

The weight ratio of catalyst-to-oil introduced into the 1.5. Itispreferred to of about 1 since ratios excessive carbon forma ratios canbe used at operate at catalyst-to-oil ratios above about l to 1.5 resultin tion. Somewhat higher weight higher pressures.

Space velocity or the weight in pounds of feed charged per hour perpound of catalyst in the reactor depends upon the age or activity levelof the catalyst, the character of the feed stock and the desired octanenumber of the product. Space velocity for a molybdenum oxide or aluminagel catalyst may vary, for example, from about 1.5 wt./hr./wt. to about0.15 Wt./hr./wt.

Since the temperature in the regenerator is maintained between about1050 and about 1200 F. the regenerated catalyst discharged to thestandpipe 39 zone will be at substantially the same temperature. Reactorcatalyst recycle through line 36 to standpipe 39 is conducted at such arate as to reduce the temperature of the freshly regenerated catalyst toa temperature of 1050 F. or below, preferably to about 950 to 1000 F.Since the cooling of the regenerated catalyst is elected by direct heatexchange with recycle reactor catalyst, the sensible heat of the freshlyregenerated catalyst is effectively transferred to the reactor zone.Moreover, because of the reduced temperature of the regenerated catalystand the heat absorption capacity of the recycle reactor catalyst, it ispossible to control the temperature and/or the time of pretreatment ofthe regenerated catalyst in transfer line 12 so as to avoid thermaldegradation or overtreatment of the catalyst. The residence time of thecatalyst in transfer line may be from 5 to 20 seconds although at thetemperatures indicated, the residence time may be as long as -15 minuteswithout having any detrimental effects upon the catalyst.

The following examples are illustrative of the present invention ExampleI In order to determine the effect of temperature on the rate and extentof reduction of molybdena, experiments were carried out at atmosphericpressure in which a molybdena-alumina catalyst and pure M003 wereconytacted with a stream of Pretreating Time, Sec

6 pure hydrogen at various tem- The data. are

peratures for extended periods of time.

summarized below.

Equivalent Form of Molybdena After 40 Hrs.

After 6 Hrs.

M0205 70% Mox0+30% M003 M020 Mo.

M020 Mo.

10% M003 on Alumina 1 C. P. M003 1 Regenerated to reduction.

These experiments show that the M003 on the alumina base isv less easilyreduced than the pure M003 (unsupported). At normal reactiontemperatures for hydroforming (about 900 F.),. it requires anexceedingly long time to reduce the molybdenum on the catalystsignificantly below an equivalent oxidation state of M0205. Attemperatures up to almost 1100 F., the pure unsupported molybdenum canbe easily reduced in H2 below M0205 but not below M002. At the hightemperatures of .1100-1200 F. desirable commercially from the standpointof simplicity of equipment, and, hence, of economics, the molybdenum canbe readily reduced below M002 and even to metallic molybdenum. This isrepresentative of over-pretreatment, and poor catalyst activity results.

at 1,200" F. to convert all molybdenum to M003 prior Example II so B./D.Unit Run No Pretreating Temperatu Valence Statel of Reactor CatalystCFR-R Clear 0.N. of Oli-430 F. Gasoline Produced Yield of 0.5-430 F.Gasoline at 90 CFR-R Octane No., Vol. Percent..

1 The valence state is dened as follows: Mo03=valence of 6.0; Moi05=valence of 5.0; MoO2=valence of 4.0. Thus, an average valence state of4.5 could be made up of equal parts ot' M002 and M0205. However, theaverage valence state alone does not give any exact information aboutvalence state of 4.5 could be and 3 parts of M002.

It is apparent from the above experiments that the more reduced statesresulted in poorer catalyst activity and selectivity, and this isprobably due to some of the molybdena b eing reduced, under the moresevere reducing conditions, to the very low oxides, or even metallicmolybdenum, which have little or no catalytic activity. For maximumcatalyst activity, an average valence state close to 5.0 is desirable,and this can readily be controlled by carrying out the pretreatment atlow temperatures.

Example III Pretreat Conditions Time, Min.

Catalyst Se lectivity (Yield of CFR-R Octane No.

Product, Vol. Percent Catalyst Activity (Octane No. of Product at 0.3WJHn/W.)

Here again itis .shown that both the. activity and `selectivity Of thecatalyst are impaired by pretreating .at high temperatures for times ofthe order of one minute or more, and the longer the time at hightemperature, the poorer the results. On the other hand, extending thetime vof pretreating at low temperatures to as much as 15 minutes has noappreciable etect on the catalyst.

Thus it is yseen from lthe above-described experiments that carrying outcatalyst pretreatment at low temperatures insures optimum catalystactivity and selectivity, and eliminates the necessity for critical anddiicult con.- trol over the time of pretreatment.

The foregoing vdescription contains a limited number of embodiments ofthe present invention. It will be understood, however, that numerousmodifications may be made by those skilled in this art without departingfrom the spirit of this invention.

What is claimed is:

1. In a process for Vhydroforniirlg hydrocarbons in contact with iinelydivided hydroforming catalyst particles comprising a group VI metaloxide upon a support in accordance with lthe uidized solids technique attemperatures of about S50-925 F., at pressures between about 50 and 5.00lbs. per sq. inch and at catalyst-to-.oil weight ratios of about `0.5 to1.5, the improvement which comprises continuously withdrawlng a streamof vcatalyst. particles from the hydroforming reaction zone,regenerating the withdrawn catalyst particles by burning carbonaceousdeposits therefrom at temperatures of l050- 1200" F., withdrawing asecond stream of catalyst from the reaction zone, mixing this secondstream ,of reactor catalyst with hot, freshly regenerated catalystparticles in sufficient amount to lower the temperature of the latter tobelow 1050 F., thereafter treating the said mixture of freshlyregenerated catalyst and 4reactor catalyst at said lower temperaturewith a hydrogen-rich gas and recycling the hydrogen treated mixture ofregenerated and reactor catalyst particles at temperatures above averagereaction zone temperatures to the reaction zone.

2. In a process for hydroforming hydrocarbons in contact vwith finelydivided hydroforming catalyst particles comprising a grop VI metal oxideupon a support in accordance with the uidized solids technique at tem-`peratures of about S50-925 F., at pressures between about 5() and 500lbs. per sq. inch and at catalyst to oil weight .ratics .of abeut 0.5to' 1.5 the improvement which comprises continuously withdrawing astream of reactor catalyst particles from a .dense fluidized "bed ofcatalyst particles' in the Vhydroforming reaction zone, discharging thestream of withdrawn catalyst particles into a regeneration zone,regenerating the said catalyst particles by `burning carbonaceousdeposits therefrom at temperatures of from, 11050f1200 F., withdrawing astream of regenerated catalyst particles from a dense, uidized bed `ofcatalyst particles in the regeneration zone, withdrawing a second streamof reactor catalyst particles from the dense iiuidized bed of catalystparticles in the hydroforming reaction zone, mixing the stream ofregenerated catalyst particles with the second stream of reactorcatalyst to lower the temperature of the regenerated catalyst to kbelow1050 F., thereafter treating the resultant mixture of regenerated andreactor catalyst particles at said lower temperature with ahydrogen-rich gas and recycling the hydrogen-treated mixture ofregenerated and reactor catalyst particles at temperatures Haboveaverage reaction zone temperatures to the hydroforming reaction zone.

3. The process as defined in claim 2 in which the second stream ofreactor catalyst is withdrawn from the upper part of the dense uidizedbed in the reaction zone and the hydrogen treated mixture of catalystparticles is recycled to the lower part of the reaction zone.

4. The process as dened in claim 2 in which the second stream of reactor,catalyst is withdrawn from the lower part of the dense luidized bed inthe reaction zone and the hydrogen treated mixture is recycled to theupper part of the dense uidized bed in the reaction zone.

5. The process as dened in claim 2 in which the second stream of reactorcatalyst is contacted countercurrently with a substantially inertstripping gas to reduce the amount of reactant materials entrained insaid second stream before it is brought into contact with the stream ofregenerated catalyst.

, vReferences Cited in the le of this patent UNITED STATES PATENTS

1. IN A PROCESS FOR HYDROFORMING HYDROCARBONS IN CONTACT WITH FINELYDIVIDED HYDROFORMING CATALYST PARTICLES COMPRISING A GROUP VI METALOXIDE UPON A SUPPORT IN ACCORDANCE WITH THE FLUIDIZED SOLIDS TECHNIQUEAT TEMPERATURES OF ABOUT 850-925* F., AT PRESSURE BETWEEN ABOUT 50 AND500 LBS. PER SQ. INCH AND AT CATALYST-TO-OIL WEIGHT RATIOS OF ABOUT 0.5TO 1.5, THE IMPROVEMENT WHICH COMPRISES CONTINUOUSLY WITHDRAWING ASTREAM OF CATALYST PARTICLES FROM THE HYDROFORMING REACTION ZONE,REGENERATING THE WITHDRAW CATALYST PARTICLES BY BURNING CARBONACEOUSDEPOSITS THEREFROM AT TEMPERATURES OF 1050*1200* F., WITHDRAWING ASECOND STREAM OF CATALYST FROM THE REACTION ZONE, MIXING THIS SECONDSTREAM OF REACTOR CATALYST WITH HOT, FRESHLY REGENERATED CATALYSTPARTICLES IN SUFFICIENT AMOUNT TO LOWER THE TEMPERATURE OF THE LATTER TOBELOW 1050* F., THEREAFTER TREATING THE SAID MIXTURE OF FRESHLYREGENERATED CATALYST AND REACTOR CATALYST AT SAID LOWER TEMPERATURE WITHA HYDROGEN-RICH GAS AND RECYCLING THE HYDROGEN TREATED MIXTURE OFREGENERATED AND REACTOR CATALYST PARTICLES AT TEMPERATURES ABOVE AVERAGEREACTION ZONE TEMPERATURES TO THE REACTION ZONE.